Everybody on here, to a greater or lesser extent, has rather the wrong end of the stick.
Whilst it's a regional/class distinction now, neither is strictly speaking more correct than the other because the differing usage comes from different kinds of meals. The nineteenth-century Northern/Midland working class would eat a hot meal like a pie or cold cuts followed by cakes or bread and jam in the evening, served with tea, thus called 'high/meat tea' to distinguish it from the earlier 'afternoon/low tea' of the upper classes, who would have had a more formal meal in the evening.
As for me, it's breakfast/brunch (depending on when it is), lunch, tea (rarely, usually just a snack here), dinner if it's cooked, out, or with family; supper if it's something from the freezer or I'm late coming back from somewhere; I've been known to say 'tea'.